This core will provide services to University of Chicago Autoimmunity Center of Excellence (UCACE) investigators to characterize the role of B lymphocytes in autoimmune pathology. There are two state-of-the-art technologies that will allow the center investigators to scrutinize autoantibody-mediated pathology. 1. Analysis of B lymphocyte specificity using recombinant monoclonal (mAb) technology. 2. Immunoglobulin light chain variable gene microarrays Finally, Drs. Weigert and Wilson will assist and provide technical support for studies of the immunoglobulin repertoire using single-cell PCR, cloning and sequencing. This approach will augment the use of light chain microarrays and human mAb analysis. The unique methodologies for scrutinizing human B cell mediated pathology will provide powerful tools to the center to facilitate our understanding of lupus and myasthenia gravis.